Save logs with uft8 encoding
Save logs with uft8 encoding

The Mesos reviewbot uses a python script to post results to
Reviewboard, and for now it can deal only with uft8 encoded
files.

Signed-off-by: Ionut Balutoiu <b43b575ec51a09bdcac4649e8775d3d209833f9f@cloudbasesolutions.com>
Co-authored-by: Alin Gabriel Serdean <5307f03f08722e6c242944d00c012bce824993f9@cloudbasesolutions.com>
Co-authored-by: Mihai Gheorghe <1dd869f0cf34091cd9af5a95e2c05b2e2650bcb9@cloudbasesolutions.com>

ionutbalutoiu/mesos-jenkins,ionutbalutoiu/mesos-jenkins